12:00 PM | **Accumulating snow tomorrow from first of three "clippers" this week...brutal cold Wednesday night/Thursday will rival the worst of last winter**

[12Z updated GFS 2-meter temperature anomaly forecast map for early Thursday; courtesy "tropicaltidbits.com"]

Discussion

Temperatures spiked yesterday in the I-95 corridor ahead of an Arctic frontal system, but much colder air has poured into the region today on very strong NW winds following the frontal passage and it’ll get even colder later this week. An active weather pattern will bring three different “clipper” systems (i.e., fast-moving) across the Northern Plains and Upper Midwest over the next several days and right into the Northeast US. The first of these will arrive early tomorrow and it will generate accumulating snow in the DC-to-Philly-to-NYC corridor generally on the order of an inch or two, but isolated three or four inch amounts are possible; especially, in the western suburbs of the District. The morning commute on Tuesday will feature numerous slick spots on the roadways in the DC and Philly metro regions as the snow should quickly stick after arrival given this increasingly cold Arctic air mass and there will likely be some re-freezing.

Another “clipper” system will arrive on Wednesday with snow shower activity in the Northeast US - potentially a few heavier snow squalls - and then brutal cold will follow for Wednesday night and Thursday. In fact, this brutal cold air mass coming for Wednesday night and Thursday will rival some of the coldest air seen all of last winter in parts of the Northeast US. Boston, for example, bottomed out all of last winter at 2 degrees above zero and that low mark from last winter is in jeopardy up there by early Thursday morning. Indeed, single digits are likely up and down the I-95 corridor in the overnight hours on Wednesday going into early Thursday and daytime highs on Thursday afternoon will be hard-pressed to escape the teens. The 12Z GFS-parallel forecast map (above) shows 2-meter temperature anomalies for early Thursday with "purples" throughout the Ohio Valley and New England representing areas featuring temperatures 20 degrees (C) or more below normal for this time of year. Yet another “clipper” system will generate numerous snow showers in the Northeast US on Friday before reinforcing Arctic air pushes in to start the weekend.